A data storage device is typically required to be set so as to perform, instead of a normal response sending user data, a predetermined response in response to a readout request for a certain logical block address (LBA) from a host device. In general, a data storage device is designed to perform a normal response in response to a readout request for a certain logical block address unless it is set to perform a predetermined response. However, with the configuration in which the setting for a logical block address is always checked before performing a normal response, it takes a long response time for the normal response. Here, it may be considered to perform reading out of user data from a recording medium and checking of the setting for a logical block address in parallel. In this case, however, it is still necessary to wait for the check result of the setting for the logical block address before sending the user data to the host device. Therefore, the response time for the normal response may be depended on the time for checking the setting for the logical block address and may become longer.